Due to increasing environmental concerns about, and due to increasing environmental regulations regarding the use of chlorofluorocarbon (CFC) cleaning fluids or of perchloroethane (PERC) cleaning fluids traditionally used in dry cleaner machines, the use of such nonflammable cleaning fluids in dry cleaners is likely to be prohibited in the near future. Volatile cleaning fluids, for example, hydrocarbon (HC) cleaning fluids such as alcohols, ketones, or petroleum fractions are cleaning fluids having excellent cleaning properties, but they may be flammable or ignitable, particularly when vapors of such volatile fluids interact with oxygen gas or with air at elevated temperature under certain conditions in a dry cleaner machine. Accordingly, a very large number of existing dry cleaner machines designed for use with nonflammable cleaning fluids cannot safely remain operative by simply exchanging the aforementioned nonflammable cleaning fluids with volatile cleaning fluids that generally have a flash point at a temperature comparable to or lower than a temperature frequently developed within a dry cleaner machine during certain operating cycles, for example, during a drying cycle.
While it is anticipated that manufacturers of dry cleaner machines will develop and manufacture a new generation of dry cleaner machines specifically designed for use with HC-based volatile cleaning fluids. The substantial financial cost of such new-generation machines presents a significant economic burden to operators of many small dry cleaning establishments. Thus, there is a strong economic incentive to devise a system and a method of operation which would adapt currently existing dry cleaner machines to the safe use of HC-based cleaning fluids, particularly if such adaptation or conversion could be accomplished by a system using readily commercially available parts or components.
The present invention is directed to providing such a system for adapting a dry cleaner machine designed for use with nonflammable cleaning fluids to the use of HC-based cleaning fluids, as will be described in more detail hereinafter. The inventive aspect of the adaptive system and the process of using same, resides in a particularly effective arrangement of commercially available components and in a particular sequence of process steps. Such a system for adapting an existing dry cleaner machine for use of HC-based cleaning fluids in accordance with the present invention has been built by the inventor and has been fully operative for several months by following a sequence of inventive process steps in operating the adapted dry cleaner machine.
Various proposals have been made to address certain aspects related to the use of flammable or ignitable cleaning fluids or cleaning solvents to safely clean or safely dry articles to be cleaned or to be dried. For example, Wellford, U.S. Pat. No. 2,639,599 proposes a closed-system dry cleaning apparatus utilizing volatile solvent in which it is proposed to introduce an inert gas into a receiving chamber of the apparatus after the work contained therein has been cleaned and the cleaning fluids have been withdrawn, so that the inert gas intermingles with remaining traces of a volatile solvent and thereby to inhibit an explosion. U.S. Pat. No. 5,241,976 to Ikawa discloses cleaning equipment for cleaning articles to be cleaned with flammable solvent in which it is proposed to supply any one of steam, steam and nitrogen, and steam and carbon dioxide to an inlet pass box and to an outlet pass box of a cleaning chamber, so as to cut off the communication of gas between a cleaning atmosphere in the cleaning chamber and the outside air. U.S. Pat. No. 5,423,921 to Saal et al discloses a method and apparatus for cleaning textiles by means of benzene-based solvents, and having a separate cleaning machine and a separate dryer, and having means for injecting protective gas into the dryer. U.S. Pat. No. 4,475,293 to Banerjee discloses a method of controlled inerting of chamber 10 atmospheres in a curing oven or a dryer in which it is proposed to withdraw solvent vapor formed in the chamber together with inert gas at a substantially constant flow rate. And U.S. Pat. No. 4,150,494 to Rothchild discloses methods and apparatus for recovering solvents in which an inert gas is supplied to the vicinity of an oven entrance and exit to substantially exclude oxygen from the oven during the curing of solvent born coatings.
As will become apparent hereinafter, none of the above cited disclosures suggest a combination of elements or a sequence of process steps which characterize a dry cleaner machine adapted to the use of hydrocarbon (HC)-based cleaning fluids in accordance with the present invention.